Rotary speed responsive apparatus



Aug. 28, 1956 E. THATCHER ROTARY SPEED RESPONSIVE APPARATUS Filed May 2.1955 United States Patent O ROTARY SPEED RESPONSIVE APPARATUS Lewis E.Thatcher, Chicago, Ill., assignor to Gaylord Products, Incorporated,Chicago, Ill., a corporation of Delaware Application May 2, 1955, SerialNo. 505,410

8 Claims. (Cl. Z110- 80) This invention relates to improvements in adevice for actuating an electric switch in response to the rate frotation of a rotating body, and refers particularly to a device of thecharacter described which is effective in operation, simple inconstruction and is operable when the rotating body rotates in eitherdirection.

In copending application for United States Patent Serial No. 505,478filed May 2, 1955, in the name of Lewis E. Thatcher, a device is shownand described for actuating or initiating a predetermined operation orproducing a predetermined signal by transforming rotation of a pluralityof associated rotating plates, to a lateral or radial movement of one ofsaid plates to actuate an electric switch in response to a predeterminedrate of rotation of said plates.

The present invention employs the basic concept set forth in saidcopending application and contemplates relatively simple, eiectiveapparatus for accomplishing the end result intended.

The features, objects and advantages of the present invention will beapparent from the accompanying drawing and following detaileddescription.

In the drawing,

Fig. 1 is a longitudinal sectional elevation illustrating a deviceembodying the concepts of the present invention.

Fig. 2 is a transverse sectional view taken on line 2-2 of Fig. 1,showing the switch in closed position.

Fig. 3 is a view similar to Fig. 2 showing the switch in open position.

Referring in detail to the drawing, 1 indicates a cupshaped housinghaving a bottom 2 and lateral wall 3. A closure disc 4 is adapted to bepositioned upon the upper edge of the wall 3 and is secured thereto bycement 5 or the like thereby providing a closed compartment 6. A boss 7is preferably formed integral with the bottom 2 and extends downwardlytherefrom. A similar boss 8 is formed integral with the closure disc 4and extends upwardly therefrom. A shaft 9 is journaled for rotation inthe bosses 7 and 8, said shaft passing through the central portion ofcompartment 6.

The shaft 9 is adapted to be rotated by external means (not shown) whichmay be coupled to said shaft. If the device 1 is used in conjunctionwith an automotive vehicle, for instance, the shaft 9 may be coupled tothe speedometer cable of the vehicle and consequently will rotate intimed relationship with said speedometer cable which, in turn, willrotate at a speed proportional to the movement of the vehicle. If aspeedometer cable is coupled to the shaft 9 the cable sheath may carry afemale coupling (not shown) which may be engageable with threads 10formed upon the outer surfaces of the bosses 7 and 8.

Although the present `device is particularly adaptable for use onautomotive vehicles to control an anticreep device which may be carriedby the vehicle or to control a speed governor, it is to be understoodthat the present invention is not to be specifically limited to thisenvironment since it will find use in many other applications.

Within the compartment 6 an upper driving member 11 ICC may be mountedupon shaft 9, the driving member 11 comprising a hub portion 12 and anoutwardly extending annular flange 13. A lower driving member 14 mayalso be positioned within the compartment 6 and may also be mounted upon'shaft 9, said lower driving member comprising hub portion 15 and anoutwardly extending annular flange portion 16. A key 17 may function torigidly secure the driving members 11 and 14 to shaft 9 whereby saiddriving members are rotated when shaft 9 is rotated.

A driven member 18 loosely embraces the hub portions 12 and 15 of thedriving members 11 and 14, said driven member being provided with acentral aperture 19 which is suiciently large to permit appreciableradial eccentric movement of the driven member with respect to shaft 9and with respect to the driving members. The driven member 18, at itsouter periphery, is provided with a rim 20 which lies outwardly from theouter peripheries of the ange portions 13 and 16 of the driving members11 and 14 respectively.

The outer faces of the driven member 18 and the op` posed faces of theflanges 13 and 16 are spaced from each other and a plastic material 21is positioned in said spaces, said plastic material being in contactwith the inner surfaces of the flanges 13 and 16 and also in contactwith the body portion of the driven member 18. The plastic material 21comprises a material preferably having appreciable viscosity and shearstrength whereby when the driving members are rotated the driven membertends to rotate through the agency of the material 21.

The outer rim 20 of the driven member 18 is provided with a slot 22, theedges defining the slot being substantially tapered. A radial projection23 is carried by the flange 13 and is preferably formed integral withsaid ange, said radial extension 23 being adapted to be postioned in theslot 22 provided in the rim 20. The arrangement is such that when thedriving members rotate, the driven member is positively rotated by theinterengagement of the projection 23 in the slot 22 and also by thefrictional resistance of the material 21 interposed between the drivingmembers and the driven member. The arrangement is also such that thedriven member 18 may move radially with respect to the driving members11 and 14 whereby said driven member may move to either an eccentric ora concentric position relative to said driving members. The radialmovement hereinbefore described is permitted by virtue of the fact thatthe projection 23 is slidably positioned within the slot 22. Of course,radial or eccentric movement of the driven member 18 with respect to the`driving members 11 and 14 is resisted by the viscosity and shearstrength of the material 21.

The material 21 preferably comprises a silicone oil, grease or paste ormay comprise relatively heavy industrial grease. However, the siliconematerial is preferred because of its physical characteristics. Forinstance, its viscosity and shear strength remain substantially constantregardless of the rate of shear. In addition, the viscosity and shearstrength of such silicones is substantially unaiected by temperaturesthroughout a relatively wide range. Consequently, the frictionalresistance between the driving members and the driven member remainssubstantially constant over a relatively wide range of operatingconditions.

A portion of the lateral wall 3 of the housing 1 is extended outwardlyto form a switch compartment 24 in which a conventional snap switch 25is positioned. The snap switch 25 comprises a frame plate 26 whichcarries a supporting ange 27, the frame plate 26 being mounted upon theinner face of wall 28 defining a portion of the compartment 24. Aresilient switch arm 29 is pivotally carried upon the flange 27 and atits end carries a contact point 30 which is juxtaposed with respect to astationary contactpoint 31 carried upon and insulated from frame 26.Contact point 31 is connected to an electrical conductor 32 which, atits opposite end, may be connected to a suitable control circuit (notshown). A second conductor 33 connects with and grounds frame 26. Theconductor 33 also connects with the same circuit to which the conductor32 is connected. When the switch arm 29 is positioned, as shown in Fig.2, contact points and 31 are closed and hence the circuit to whichconductors 32 and 33 are connected is energized. When the switch arm 29is in the position shown in Fig. 3, the contact points 3i) and 31 areseparated and the external circuit is deenergized. A pressure bar 34 ispivotally mounted upon the flange 27 and is acted upon by the lower endof the resilient switch arm 29. The resiliency of the arm 29 exerts aresilient force upon the pressure arm 34 tending to rock said pressurearm in a counterclocltwise direction, as viewed in Figs. 2 and 3.

At the outer end of the pressure arm 34 an abutment plate 35 is carried,said plate being pivotally secured, as at 36, to the end of pressure arm34. The abutment plate 35 comprises a pair of oppositely extending arms37 and 38, arrn 37 having an arcuate Contact linger 39 and arm 38 havingan arcuate contact finger 40. By virtue of the resilient force actingupon the pressure arm 34 the plate 35 is urged toward the outerperiphery or rim 20 of the driven member and the linger portions 39 and40 make resilient pressure contact with the periphery of rim 2t).Accordingly7 the resilient pressure exerted upon arm 34, through thelingers 39 and 40, tends to urge the driven member 18 to an eccentricposition with respect to the driving members 11 and 14.

As has been described in the application for patent, hereinbeforeidentified, two opposing forces are in operation, the force of arm 34being applied by the fingers 39 and 40 radially to the driven member 18,which will be hereinafter referred to as the active force, and the forceof friction between the driving and driven members, which willhereinafter be referred to as the reactive force. The active force tendsto move the driven member 18 to an eccentric position relative to thedriving members 11 and 14 and this force is opposed by the reactiveforce. When the shaft 9 is stationary the reactive force comprisesessentially the viscous resistance and shear resistance of the material21. When the shaft 9 rotates, the reactive force is also a function ofthe rate of rotation.

When the shaft 9 is stationary, the active force overbalances thereactive force and the driven member 1S will be moved radially to aneccentric position. if shaft 9 is then rotated, the reactive force isaugmented and, depending upon the constants employed, which will behereinafter more fully discussed, a rate of rotation will be reachedwhere the active and reactive forces become equal. lt will be noted thatthe driven member 18 is positively rotated by the interengagement of theprojection 23 in slot 22. Hence, if the driven member is initiallyeccentric below the critical balancing speed, mentioned hereinbefore,the driven member will remain eccentric in a direction away from theactive force. However, as the rate of rotation increases the degree ofeccentricity will decrease until at said critical speed the drivenmember 1S will move to substantial concentricity with the drivingmembers. When this condition is reached, arm 34 will have been moved tothe point where switch 25 is actuated to closed position.

If the rate of rotation is sufficiently high the active force will beunable to radially shift the driven member from its eccentric positionif it were initially eccentric and, hence, the driven member wouldremain eccentric to the driving members but the eccentricity wouldcontinuously change relative to the active force, that is, driven member18 will continuously rotate eccentrically with respect to the drivingmembers.

To avoid this action, a stop 41 is mounted upon base 2 in the path oftravel of plate 35 whereby eccentricity of the driven member toward theactive force is inhibited. Accordingly, when the rotation of shaft 9exceeds the critical speed, the driven member having been moved toconcentric position at the critical speed, will remain at concentricposition. Hence, switch 25 will be actuated to closed position at saidcritical speed and will remain closed at all speeds thereabove.

When shaft 9 slows down to a speed below the critical speed, the activeforce will predominate and, hence, the driven member will be moved to aneccentric position away from said active force and switch 25 will beactuated to open position.

To construct a device which will act at a predetermined critical speed,the following factors must be observed: The strength of spring 29; thephysical characteristics of the material 21 as to viscosity and shearstrength; the thickness of the layers of material 21, and the areas ofthe driving and driven members wetted by the material 21. Of course, thegreater the strength of spring 29 the greater will be the active force.With a material of relatively high viscosity and high shear strength arelatively high reactive force may be obtained and vice versa. Thereactive force would also be inversely proportional to the thickness ofthe layers of material and would be directly proportional to the wettedareas of the driving and driven members. Thus, devices may beconstructed responsive to predetermined rates of rotation overrelatively wide ranges of rates of rotation.

In the present invention it will be noted that although the drivenmember is radially movable a limited degree with respect to the drivingmembers 11 and 14, the driven member is ultimately positively drivenrotationally by the driving member 13. Thus rotation of the drivenmember it? does not depend upon the material 21.

In addition, by virtue of the physical construction of plate 35, thedevice is operative to perform its intended function regardless of thedirection of rotation thereof.

It will be apparent to any one skilled in the art that manymoditications may be made in the present invention without departingfrom the spirit thereof, and, hence, it is not intended that theinvention be limited to the precise structure shown and described exceptas necessitated by the appended claims.

I claim as my invention:

l. A device for actuating an electric switch in response to the rate ofrotation of a rotating body which comprises, driving plate rotatableabout an axis transverse to its face, a driven plate embracing said axisand eccentrically movable with respect to said axis and disposed insubstantially plane-parallel relationship to said driving plate, aradial projection carried by said driving plate slidably engageable in aslot provided in the periphery of said driven plate whereby said drivenplate rotates with said driving plate but may move eccentrically withrespect to said driving plate, an electric switch, a spring-pressedactuating arm for said switch, a contact plate carried by said actuatingarm and resiliently contacting the periphery of said driven plate tourge resiliently said driven plate to an eccentric position with respectto the driving plate when said plates are stationary, means forfrictionally engaging the opposed surfaces of the driven plate anddriving plate, and means for rotating said driving plate to urge saiddriven plate toward concentric position with respect to said drivingplate and actuate said switch against the resilient force of saidactuating arm.

2. A device for actuating an electric switch in response to the rate ofrotation of a rotating body which comprises, a driving plate rotatableabout an axis transverse to its face, a driven plate embracing said axisand eccentrically movable with respect to said axis and disposed insubstantially plane-parallel relationship to said driving plate, aradial projection carried by said driving plate slidably and rockablyengageable in a slot provided in the periphery of said driven platewhereby said driven plate rotates with said driving plate but may moveeccentrically with respect to said driving plate in a plane parallel tothe plane of said driving plate, an electric switch, a springpressedactuating arm for said switch, a contact plate carried by said actuatingarm and resiliently contacting the periphery of said driven plate tourge resiliently said driven plate to an eccentric position with respectto the driving plate when said plates are stationary, means forfrictionally engaging the opposed surfaces of the driven plate anddriving plate, and means for rotating said driving plate to urge saiddriven plate toward concentric position with respect to said drivingplate and actuate said switch against the resilient force of saidactuating arm.

3. A device for actuating an electric switch in response to the rate ofrotation of a rotating body which comprises, a driving plate rotatableabout an axis transverse to its face, a driven plate embracing said axisand eccentrically movable with respect to said axis and disposed insubstantially plane-parallel relationship to said driving plate, aradial projection carried by said driving plate slidably engageable in aslot provided in the periphery of said driven plate whereby said drivenplate rotates with said driving plate but may move eccentrically withrespect to said driving plate, an electric switch, a spring-pressedactuating arm for said switch, a substantially U-shaped cona tact platepivotally carried by said actuating arm, the arms of said contact plateresiliently contacting the periphery of said driven plate to urgeresiliently said driven plate to an eccentric position with respect tothe driving plate when said plates are stationary, means forfrictionally engaging the opposed surfaces of the driven plate anddriviing plate, and means for rotating said driving plate to urge saiddriven plate toward concentric position with respect to said drivingplate and actuate said switch against the resilient force of saidactuating arm.

4. A device for actuating an electric switch in response to the rate ofrotation of a rotating body which comprises, a driving plate rotatableabout an axis transverse to its face, a driven plate embracing said axisand eccentrically movable with respect to said axis and disposed insubstantially plane-parallel relationship to said driving plate, aradial projection carried by said driving plate slidably engageable in aslot provided in the periphery of said driven plate whereby said drivenplate rotates with said driving plate but may move eccentrically withrespect to said driving plate, an electric switch, a spring-pressedactuating arm for said switch, a substantially cl-shaped contact platepivotally carried by said actuating arm, the arms of said contact plateresiliently contacting the periphery of said driven plate to urgeresiliently said driven plate to an eccentric position with respect tothe driving plate when said plates are stationary, relatively viscousplastic means for frictionally engaging the opposed sur faces of thedriven plate and driving plate, and means for rotating said drivingplate to urge said driven plate toward concentric position with respectto said driving plate and actuate said switch against the resilientforce of said actuating arm.

5. A device for actuating an electric switch in response to the rate ofrotation of a rotating body which comprises, a driving plate rotatableabout an axis transverse to its face, a driven plate embracing said axisand eccentrically movable with respect to said axis and disposed insubstantially plane-parallel relationship to said driving plate, aradial projection carried by said driving plate slidably engageable in aslot provided in the periphery of said driven plate whereby said drivenplate rotates with said driving plate but may move eccentrically withrespect to said driving plate, an electric switch, a spring-pressedactuating arm for said switch, a substantially U-shaped contact platepivotally carried by said actuating arm, the arms of said contact plateresiliently contacting the periphery of said driven plate to urgeresiliently said driven plate to an eccentric position with respect tothe driving plate when said plates are stationary, a relatively viscousplastic silicone for frictionally engaging the opposed surfaces of thedriven plate and driving plate, and means for rotating said drivingplate to urge said driven plate toward concentric position with respectto said driving plate and actuate said switch against the resilienttorce of said actuating arm.

6. A device for actuating an electric switch in response to the rate ofrotation of a rotating body which comprises, a substantially circulardriving plate rotatable about an axis transverse to its face, asubstantially circular driven plate embracing said axis andeccentrically movable with respect to said axis and disposed insubstantially planeparallel relationship to said driving plate, acircular rim carried by the outer periphery of said driven plate, aradial projection carried by said driving plate slidably engageabl'e ina slot provided in the rim of said driven plate whereby said drivenplate rotates with said driving plate but may move eccentrically withrespect to said driving plate, an electric switch, a spring-pressedactuating arm for said switch, a contact plate carried by said actuatingarm and resiliently contacting the rim of said driven plate to urgeresiliently said driven plate to an eccentric position with respect tothe driving plate when said plates are stationary, means forfrictionally engaging the opposed surfaces of the driven plate anddriving plate, and means for rotating said driving plate to urge saiddriven plate toward concentric position with respect to said drivingplate and actuate said switch against the resilient force of saidactuating arm.

7. A device for actuating an electric switch in response to the rate ofrotation of a rotating body which comprises, a pair of spaced drivingplates rotatable about an axis transverse to their faces, a driven plateembracing said axis and eccentrically movable with respect to said axisand disposed in substantially plane-parallel relationship to saiddriving plates, a radial projection carried by one of said drivingplates slidably engageable in a slot provided in the periphery of saiddriven plate whereby said driven plate rotates with said driving platesbut may move eccentrically with respect to said driving plates, anelectric switch, a spring-pressed actuating arm for said switch, acontact plate carried by said actuating arm and resiliently contactingthe periphery of said driven plate to urge resiliently said driven plateto an eccentric position with respect to the driving plates when saidplates are stationary, means for frictionally engaging the opposedsurfaces of the driven plate and driving plates, and means for rotatingsaid driving plates to urge said driven plate toward concentric positionwith respect to said driving plates and actuate said switch against theresilient force of said actuating arm.

8. A device for actuating an electric switch in response to the rate ofrotation of a rotating body which comprises, a driving plate rotatableabout an axis transverse to its face, a driven plate embracing said axisand eccentrically movable with respect to said axis and disposed insubstantially plane-parallel relationship to said driving plate, aradial projection carried by said driving plate slidably engageable in aslot provided in the periphery of said driven plate whereby said drivenplate rotates with said driving plate but may move eccentrically withrespect to said driving plate, an electric switch, a spring-pressedactuating arm for said switch, a contact plate carried by said actuatingarm and resiliently contacting the periphery of said driven plate tourge resiliently said driven plate to an eccentric position with respectto the driving plate when said plates are stationary, means forfrictionally engaging the opposed surfaces of the driven plate anddriving plate, means for rotating said driving plate to urge said drivenplate toward concentric position with respect to said driving plate andactuate said switch against the resilient force ot said actuating arm,and stop means for abutting said actuating arm to prevent eccentricmovement of said driven plate toward said actuating arm.

No references cited.

